In paper forms the specific sub-questions cannot be hidden from the user when they are not relevant to them - but in interactive forms this is relatively easy to do. Use progressive revealing as much as possible in your form design to shield your users from questions they do not need to see.

Use appropriate response mechanisms. Paper forms have the disadvantage that users can miss, or simply disregard, an instruction. For example, only tick/check one box from a list of 15 or 20 options. In this context interactive forms can be programmed so that the user can only tick/check one (known as a radio button as distinct from check-boxes), or presented with the options in a drop-down menu from which the user can only select one.